MYTILIDAE 35 3 



purplish and white. Anterior end has two very tiny purplish teeth. Beyond 

 the ligament (posterior end) there are 5 to 6 very tiny, equal-sized teeth on 

 the edge of the shell. Compare with B. citrinus, which is more elongate. 



Brachidontes stearnsi Pilsbry and Raymond Stearns' Mussel 



Santa Barbara, California, to Oaxaca, Mexico. 



/4 to I inch in length, obtusely carinate, with numerous coarse, beaded, 

 radial ribs which bifurcate. Color brownish purple on the dorsal half, straw- 

 yellow to brownish yellow on the flattened ventral half. Hinge on dorsal 

 edge with about a dozen very tiny bar-like teeth. Usually found in colonies 

 in crevices of stones. Two small clams, Lasaea cistula Keen and L. subviridis 

 Dall, attach themselves to the byssus of this species. Do not confuse B. 

 stearjisi with Septifer bifurcams, with which it often lives. B. multijormis 

 Carpenter and B. adamsianus Dunker are closely related species, if not mere 

 forms, found in the Panamic province. 



Subgenus Ischadiwn Jukes-Brown 1905 

 Brachidontes recurviis Rafinesque Hooked Mussel 



Plate 3511 



Cape Cod to the West Indies. 



I to 2% inches in length, flattish, rather wide, with numerous wavy 

 axial ribs. Color outside a dark grayish black, inside a purplish to rosy 

 brown with a narrow blue-gray border. At the umbonal end there are 3 to 

 4 extremely small, elongate teeth on the edge of the shell. The anterior end 

 of the shell is strongly hooked. This ■s\as known as M. hamatus Say and has 

 sometimes been placed in the genus Mytilus. 



Genus Amygdahnn Megerle von Miihlfeld 181 1 



Shell thin, very smooth, often with colored, cobwebby designs. These 

 clams build nests for themselves with a copious supply of byssal threads. 



Amygdaluni papyria Conrad Paper Mussel 



Plate 28i 



Texas and Maryland to Florida. 



I to 1% inches in length, elongate, smooth, glistening, fragile, and 

 colored a delicate two-tone of bluish green and soft yellowish brown. In- 

 terior iridescent-white. The ligament is very weak and thin. A. sagittata 

 Rehder, sometimes dredged off^ Florida and Mississippi, is very shiny, ivory- 

 white, half of each valve with fine, gray, cobwebby streaks. The umbo is 

 reinforced inside by a very small, smooth column or rib. 



